Business forms with pressure activated adhesive or cohesive have become increasingly popular because of numerous practical advantages associated therewith. These adhesives (such as sold by Toppan Forms Company of Japan with a trade designation TN124, and as disclosed in U.S. Pat. Nos. 4,918,128, 5,190,818, 5,314,944 and 5,427,851) require application of a substantial force in order to effect sealing. A wide variety of different pieces of pressure seal equipment have been developed for that purpose, such as sold by Moore U.S.A., Inc. of Lake Forest, Ill. under the trademark "SpeediSealer", and such as shown in U.S. Pat. Nos. 5,169,489, 5,378,303, 5,397,427 and 5,527,416 (the disclosures of which are hereby incorporated by reference herein). While this commercial equipment is very useful in effecting proper sealing and handling of business forms with pressure activated adhesive or cohesive, it would be desirable to reduce the weight of the equipment, and provide a lower cost to the end user.
According to the present invention a method is provided for sealing business forms connecting longitudinal and transverse patterns of pressure activated cohesive or adhesive (requiring a sealing force of at least about 50 lbs. per lineal inch, typically between about 100-200 lbs. per lineal inch) using equipment at lower cost than conventional systems such as sold by Moore U.S.A., Inc. under the trademark "SpeediSealer". By using a particular serrated or ribbed roll, and typically a larger diameter substantially smooth surfaced roll, it is possible to seal a form by passing it through only one nip. Because of the serrations or ribs, at least 50%, but less than 90%, of the cohesive is compressed. The reduction in surface compressions (that is the serrations or ribs versus the solid roll) compresses less cohesive per square inch, thus requiring less pressure and smaller roll circumference, reducing cost.
According to one aspect of the present invention a method of sealing a business form having longitudinal and transverse patterns of pressure activated cohesive or adhesive (such as described above) requiring a sealing force of at least about 50 lbs. per lineal inch is provided. The method comprises: (a) moving the business form in a first direction substantially parallel to a longitudinal pattern of pressure activated cohesive or adhesive thereon; and (b) while the form is moving in the first direction passing the form through a nip between a substantially smooth surfaced first roll and a serrated or ribbed second roll, the roller rotated about substantially parallel axes of rotation, so as to compress at least 50%, but less than 90%, of each of the longitudinal and transverse patterns of pressure activated adhesive or cohesive, by applying a force of over 50 lbs. per lineal inch at the serrations, or ribs.
In the method (b) is preferably practiced to effect complete sealing of the business form without passage through another roller nip, and to apply a compressive force of between about 100-200 lbs. per lineal inch at the serrations or ribs. If the first and second rolls each have an overlapping length of about 6 inches or more, then the method preferably further comprises (c) applying a reinforcement force to the serrated or ribbed roll to prevent bowing thereof.
In the method, preferably (b) is practiced using a second roll with serrations approximately one-half of which have a first angled orientation and approximately one-half of which have a second angled orientation substantially opposite the first angled orientation, each orientation making an angle of at least about 10.degree. to a plane substantially transverse to the axis of rotation of the second roll. Also, (b) may be further practiced using serrations or ribs each having a first dimension substantially parallel to the axis of rotation of between about 0.04-0.1 (e.g. about 1/16) inches, with spaces therebetween of between about 0.02-0.1 (e.g. about 1/32-1/16) inches.
Also, according to the invention, typically (a) and (b) are practiced using Z-fold, C-fold, V-fold, or double fold forms having at least four transversely spaced longitudinal strips of pressure activated cohesive, two strips adjacent each longitudinal edge of the form cooperating with each other, and at least two cooperating transverse strips of pressure activated cohesive. Also, preferably (b) is practiced using a first roll having a diameter of at least twice that of the second roll, and each of the first and second rolls has a length dimension parallel to the axis of rotation thereof of between about 4-12 inches.
According to another aspect of the present invention a sealing roll assembly is provided comprising the following components: A first smooth surfaced roll rotatable about a first axis of rotation having a length dimension parallel to the first axis of rotation of between about 4-12 inches and having a first diameter. A second roll having a ribbed or serrated surface and rotatable about a second axis of rotation parallel to the first axis and having a length dimension parallel to the second axis of between about 4-12 inches, and a second diameter. And wherein the second diameter is less than half the first diameter.
If each of the first and second rolls has a length of more than about 6 inches, the assembly further comprises a reinforcement roll engaging the second roll and rotatable about a third axis parallel to the first and second axes and substantially in-line therewith, to prevent bowing of the second roll. Typically the ribs or serrations have a first dimension substantially parallel to the axis of rotation of between about 0.04-0.1 inches, with spaces therebetween of between about 0.02-0.1 inches. Also, preferably approximately one-half of the serrations or ribs have a first angled orientation, and approximately one-half have a second angled orientation substantially opposite the first angled orientation, each orientation making an angle of at least about 10.degree. to a plane substantially transverse to the second roll axis of rotation.
According to another aspect of the present invention a sealing roll assembly is provided comprising the following components: A first smooth surfaced roll rotatable about a first axis of rotation having a length dimension parallel to the first axis of rotation of between about 4-12 inches and having a first diameter. A second roll having a ribbed or serrated surface and rotatable about a second axis of rotation parallel to the first axis and having a length dimension parallel to the second axis of between about 4-12 inches, and a second diameter. And wherein the ribs or serrations have a first dimension substantially parallel to the axis of rotation of between about 0.04-0.1 inches, with spaces therebetween of between about 0.02-0.1 inches. Additional details of the roll assembly may be as described above.
It is a primary object of the present invention to provide a method and assembly for the relatively inexpensive yet effective sealing of business forms having pressure activated cohesive or adhesive. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.